beta-(1, 2, 4-triazolyl-3)-alanine and its salts and the preparation thereof



United States Patent cc 2,719,849

Patented Oct. 4, 1955 the free amino acid, followed by isolation of theamino I acid. 2,719,849 The compounds of this invention are usefulchemical fl-(l,2,4-TRIAZOLYL-3)-ALANINE AND ITS SALTS intermediates. Forexample, /9-( l,2,4-triazolyl-3)-alanine, AND THE PREPARATION THEREOF 5can be decarboxylated to 3-(j3-aminoethyD-l,2,4-triazole,

an antihypertensive agent disclosed in our co-pending ap- CameronAmsworth and Reuben G. Jones lndlanapoiis Iud., assignors to Eli Lillyand Company Indianapolis: phcanon serial filed Apnl 1953' In addition,;8-(l,2,4-triazolyl-3)-alanine and its salts are a corpommm of Indlanauseful as metabolic blockers or antagonists for histidine.

N0 Dlawillg- Applicafioll February 1954, 10 Detailed methods for thepreparation of illustrative Serial 408,283 compounds of this inventionare as follows:

8 Claims. (Cl.,260-308) EXAMPLE 1 i I p-(l,2,4-'rRIAz0LYL-3)-ALAN1NEThis invention relates to a novel amino acid and its preparation ofethyl 3-(1 2 44 i dl b x l t salts. More particularly, it relates to asubstituted 32 g. of 3-( 1,2,4-triazole)-carboxylic acid are suspend- .3g 325 :25 6 acid of this invention is 2 4411; ed in 500 ml. of absoluteethanol and saturated with gasazolyl 3 alanine, and can be representedby the following eous hydrogen chloride at 0 C. The mixture is allowedconventional formula: to stand for three days at room temperature. Thesolvent 18 then removed 1n vacuo and the resulting solld residue,

N v consisting of ethyl 3-(1,2,4-Qtriazole)-carboxylate hydro-AOHz-GH-GOOH I chloride, is washed with saturated sodium bicarbonate HNL NH, solution. At this point, the quantity of solid ethyl3-(l,2,4-triazole)-carboxylate which precipitates is sepa- Because ofthe presence of both carboxyl and amine rated by filtration. Thefiltrate is extracted with ethyl groups in the amino acid, the compound,like other amino acetate, and on removal of the ethyl acetate in vacuo,a acids forms a zwitter-ion. Moreover, the multiplicity further quantityof ethyl 3-(1,2,4-triazole)-carboxylate of acidic and basic groupings inthe molecule permits the remains. The solid ester fractions are combinedand reformation of both monoand di-salts with cations and crystallizedfrom absolute ethanol. 24 g. of crystalline anions. Illustrativeexamples of anionic salts'include the ethyl3-(1,2,4-triazole)-carboxylate melting at about 178 hydrochloride,hydrobromide, sulfate, phosphate, tri- C. is obtained.

chloroacetate, benzene-sulfonate salts, and the like. Illus-Analysis;-Calculated for CsHINsOa: C, 42.55; H,

trative examples of cationic salts include the sodium, po- 5.00; N,29.78. Found: C, 42.33; H. 4.81; N, 29.79. tassium, calcium, barium,silver, mercury, ammonium,

substituted ammonium salts, and the like. Preparation of ,6-(1,2,4triazolyl-3)-alanine can be prepared by the fol- Q hydrochlor'de lowingseries of reactions: 3-(1,2,4-triazole)-carboxylic T a mi tu e f 8,5 flithium aluminum hydride acid, P p y the method of Andreocci [Beilsteing and 200 ml. of tetrahydrofuran is added a solution of 280 (1937)] isesterified, and the ester is reduced tothe 40 32 g. of ethyl3-(1,2,4-triazole)-carboxylate in 500 ml.

corresponding carbinol. The hydrochloride of this car oftetrahydrofuran. After the immediate reaction has binol is formed and isthen C nv rted to 3- hl 'O Y1-- subsided, the mixture is refluxed-for 4hours, and is then 1,2,4-triazole hydrochloride by treatment withthionyl treated with 10 ml. of methanol followed by- 50 ml. of achloride. The 3-chloro compound is condensed with 50-50 mixture ofmethanol and water. The mixture'is diethyl formylaminomalonate ordiethyl acetamidomalofiltered,'and the filter cake, which consistschiefly of innate in the presence of a sodium ethylate and theconorganic substances, is extracted twice with hot methanol densationproduct, the oz acylamino a 1,2,4 triazolyl and once with hot water. Thecombined extracts are methyl)-malonic ester is hydrolysed anddecarboxylated evaporated in vacuo and the resulting residue isdissolved in an acid medium, yielding an acid addition salt of inethanol. A small part of this residue consists offi-(l,2,4-triazolyl-3)-alanine. ethanol-soluble inorganic hydroxides,and Dry Ice (solid This series of transformations can be represented byC02) is therefore added to convert these hydroxides to the followingequation: the corresponding carbonates. These carbonates, being N N ICOOH H+ WCOOCEI; LiA1H4 I CHzOH H01 H H H N i N Diethyl WCHIOH.HC1 S001;mOHgCLHCl formylaminomalonate L, NaOEt H/ H/ N COOCzHs A d N 00011 N(W-CH:CNHOHO mCHz-CNH2-2H(Jl heat O-CHz-CH-COOHJHCI I Hydrolysis N NCOOCzH; (H01) N L COOH N L NH2 H H H From the salt, the free amino acidcan be prepared insoluble, separate from solutionand are removed byfilby methods applicable to amino acids generally, such as tration. Onevaporation of the resulting filtrate in vacuo,

treatment with a suitable base; e. g., aniline, to liberate an oilyresidue remains, consisting of 3-hydroxymethy1- 1,2,4-triazole. This oilis dissolved in dilute hydrochloric acid and on removal of the solventin vacuo, yields a White solid, consisting ofS-hydroxyrnethyl-1,2,4-triazole hydrochloride. This solid, aftercrystalization from a mixture of methanol and ether, melts at about150153' C. and weighs 23 g:

Analysis. Caleulated for CsHsClNzO: C, 26.58; H,- 4.46. Found: C, 26.74;H, 4.62.

Preparation of 3-chl oromethyl-1,2,4=triazole hydrochloride To 6.8 g. of3 hydroxymethyl-1,2,4-triazole hydrochloride are added 100 ml. ofthionyl chloride, and the mixture is refluxed for 4 hours. Upon cooling,a white solid consisting of 2-chloromethyl-1,2,4-triazole hydrochlorideseparates from solution. About 3 volumes of dry diethyl ether are addedto complete the precipitation of this compound and the resultingsuspension is filtered. Recrystallization of the filtered material froma mixture of alcohol and ether yields 7.7 g. of crystallinei-chlor'omethyl- 1,2,4-triazole hydrochloride melting at about 115-116"C.

Analysis.Calculated for Cal-IsClzNs'i C, 23.40; H, 3.27; N, 27.29.Found: C, 23.55; H, 3.38; N, 27.42.

Preparation of fi-(1,2,4-triazolyl-3)-alanin dihydrochloride 2.3 g. ofsodium are added to 100 ml. of absolute ethanol and after all the sodiumhas reacted, 10.2 g. of diethyl formylaminomalonate are added. Theresulting mixture is cooled to C., 7.7 g. of S-chloromethyh1,2,4-triazole hydrochloride dissolved in 100 ml. of absolute ethanolare added and the mixture is stirred for 6 hours. The alcohol is thenremoved in vacuo, and the solid residue is dissolved in 200 ml. of 2normal hydrochloric acid. This acidic, aqueous solution is firstextracted with ethyl acetate and then is made basic with sodiumcarbonate. The alkaline mixture is extracted with a mixture of equalparts of diethyl ether and ethyl acetate, and the extract is thenevaporated in vacuo to remove the solvent, yielding diethyl(l,2,4-triazolyl-3-rnethyl) formylaminomalonate as an oil. This oil isdissolved in 50 ml. of concentrated hydrochloric acid, and the solutionis heated for about 10 hours on the steam bath, thereby hydrolysing thesingle amide and the two ester groups and causing the loss of one of thecarboxyl groups. The resulting acidic solution of;8-(1,2,4-triazolyl-3)-alanine is evaporated to dryness in vacuo. Asolid residue of B-(1,2,4-triazolyl-3)-alanine dihydr'ochloride remainsand this compound is purified by recrystalization from a mixture ofether and ethanol. The dihydrochloride forms hygrosc'opic crystals whichhave no definite melting point.

EXAMPLE 2 fl-(l,2,4-i1zrAzoLYL-3)-ALANiNe 7 g. of[3-(1,2,4-triazolyl-3)-alanine dihydrochloride are dissolved in 100 m1.of absolute ethanol and about 7 g. of aniline are added.;8-(1,2,4-triazolyl-3) alanine precipitates and is removed byfiltration. It is purified by crystalization from aqueous ethanol. g. ofsubstantially pure material is obtained which melts at about 263- 264"C.

Analysis.-Calculated for C5H8N4022 C, 38.46; H, 5.16; N, 35.88. Found:C, 38.38; H, 5.28; N, 35.48.

4 EXAMPLE 3 p-(l,2,4-'mnizoLYL-3)-ALANiNE DINI'IRATE 5 g. of;3-(1,2,4-triazolyl-3)-alanine are dissolved in dilute nitric acidcontaining two equivalents of nitric acid. On evaporation of the waterin vacuo, a solid residue of ;8-(1,2,4-triazolyl-3)-alanine dinitrateremains. It is crystallized from an ethanol-ether mixture.

. EXAMPLE 4 3-(1,2,4-rnmzoLYL-3-) ALAN1NE HYDROBROMIDE 0.32 mol of HBr(as 48% solution in water) is diluted with 50 ml. of water and 5 g. of13-(l,2,4-triazolyl3)- alanine are dissolved in the resulting solution.On evaporation of the water invacuo, a solid residue of 3-(1,2,4-triazolyl-3)-alanine hydrobror'nide remains.

Other monoand dianionic salts of fl-(1,2,4-triazolyl 3)-'alanine can beobtained as described above by reacting the amino acid with a solutioncontaining one or two molecular equivalents, respectively, of thedesired acid. If the acid is non-volatile or if the acid is a volatilestrong acid (HCl, HBr and the like), the salt is readily recovered byremoving the solvent by evaporation in vacuo. If the acid is a volatileweak acid, the sale preferably is isolated from its solution by theaddition of a miscible solvent in which the salt is relativelyinsoluble.

EXAMPLE 5 MoNo-SonrUM SALT or ,3-(1,2,4-rniAzoLYL-3)-ALAr-iiNE ml. ofwater solution containing 5 g. of St-(1,2,4- triazolyl-3)-alanine areneutralized to a pH of about 6 with dilute sodium hydroxide. A pH metercan be used to follow the neutralization. On evaporation of the solutionto dryness in vacuo, a solid residue remains consisting of themono-sodium salt of 8-(l,2,4-triaZolyl-3)-alanine. EXAMPLE 6 Dr-SiLvERSALT on ,B(l,2,4TRIAZOLYL3)-ALANINE T050 ml. of hotlwater containingabout 5 g. of fi-(1,2,4- trazolyl-3)-a lanine are added with stirring8.8 g. of silver carbonate. Thesolid residue remaining after evaporatonconsists of the di-silver salt of fl-(1,2,4-triazolyl-3)- alanine. V

Other monoand (ii-cationic salts of fi-(l,2,4-triazolyl'- 3)-alani necan be prepared as described above, by react ing'the amino acid with oneor two molecular equivalents, respectively, of the desired base.

We claim: I

l. A compound chosen from the class consisting of;8-(1,2,4-triazolyl-3)-alanine, and its metal salts, and its acidaddition salts.

2. B-( 1,2,4-triazolyl-3 -alanine.

3. A metal salt of ;8-(1,2,4-triazolyl 3) alanine.

4. The mono-sodium salt of fi-(l,2,4-triazolyl-3) alanine.

5. An acid addition salt of ,8-(1,2,4-triazolyl-3)-alanine.

6. 8-(1,2,4-triaZolyl-3)-alanine dihydrochloride.

7. 3-chloromethyl-1,2,4-triazole.

8. 3-hydroxymethyl-1,2,4-triazole.

References Cited in the file of this patent Sheehan et al., J. Am. Chem.Soc., vol. 71, pp. 1436- 40 (1949).

1. A COMPOUND CHOSEN FROM THE CLASS CONSISTING OF B-(1,2,4-TRIAZOLYL-3)-ALANINE, AND ITS METAL SALTS, AND ITS ACID ADDITION SALTS.
 7. 3-CHLOROMETHYL-1,2,4-TRIAZOLE.
 8. 3-HYDROXYMETHYL-1,2,4-TRIAZOLE. 